Many herbicides are reported in the prior art. However, the herbicidal effectiveness of a given compound cannot be predicted from an examination of the substituent groups of the compound and often quite closely related compounds, which will have quite different weed control abilities. Various herbicides or the isomers of the same herbicide may have overlapping or complementary areas of activity or selectivity, and can thus be useful to control a variety of weeds upon application of a composition. Furthermore, the various known herbicides are not completely effective. An ideal herbicide should give selective weed control, over the full growing season, with a single administration. It should be able to control all common weeds by controlling their growth and reproduction as the seed, the germinating seed, the seedling, and the growing plant.
Although the enantiomers of chiral substances have the same physicochemical properties, their biochemical activities can be quite different because biochemical processes usually show high stereo- or enantioselectivity.
The “active” enantiomer of a chiral chemical may have the desired effect on a target species, whereas the other enantiomer may not. It is advisable to use only the biologically active enantiomers, thereby reducing the total amount of chemical pollutants released into the environment.
Many agrochemicals have chiral structures. For example, about 30% of currently registered pesticide active ingredients contain one or more chiral centers. Herbicides are used to control the growth of undesired vegetation, and they account for most of the agrochemicals in use today. Some chiral herbicides are sold as purified, optically active isomers, but for economic reasons, many others are still used as racemates. Different enantiomers of chiral herbicides can have different enantioselective activities on target weeds and different toxic effects on non-target organisms because of their enantioselective interactions with enzymes and biological receptors in organisms but the herbicidal selectivity of a specific isomer is not predictable.
N,N-diethyl-2-(α-naphthoxy)propionamide is known as napropamide, and its racemic mixture is generally marketed under trade name as DEVRINOL® (napropamide). It is used for pre-emergence control of annual grasses and broad-leaved weeds in many crops and plantations.
The second carbon atom at the propionamide group in napropamide has a hydrogen atom, a methyl group, a naphthoxy moiety and a carboxamide group thereby forming a chiral center. Hence the molecule can exist in two chiral stereoisomers: D or (R) and L or (S)-isomers:

Napropamide is a selective systemic herbicide absorbed by roots and translocated acripetally. It inhibits root development and growth.
Unsolved problems in this area include widely differing sensitivities of crop plants against herbicidal chemicals as well as the fact that repression of one weed species may cause increased growth of another competing weed species, and that some weeds tend to become resistant against previously effective herbicides.
U.S. Pat. No. 3,718,455 discloses new organic compounds of formula I used as herbicides:

This structure includes the compound Napropamide (Compound No. 54 and Compound No. 55). The herbicidal activity of compounds 1 to 22 is reported on crabgrass, annual bluegrass, watergrass and foxtail. This patent discloses that Compound No. 54 and Compound No. 55 possess good herbicidal activity and can be used as pre-emergent and post-emergent herbicides (Table III). This patent disclosure did not investigate and does not indicate any differential selectivity of D-Napropamide towards different weed classes or types.
WO2009004642 discloses a process for manufacture of high purity D-(−)-N,N-diethyl-2-(α-naphthoxy)propionamide from L-2-Halopropionic Acid or (s)-(−)-2-Halopropionic Acid and composition comprising high purity D-(−)-N,N-diethyl-2-(α-naphthoxy)propionamide. Again, this patent disclosure did not investigate and does not indicate any differential selectivity of D-Napropamide towards different weed classes or types.
There is a need in the art for enhanced uses of D-Napropamide and for improved methods of herbicidal control by using D-Napropamide.